Echinocandins as Biotechnological Tools for Treating Candida auris Infections

Effectiveness of a sodium hypochlorite isotonic solution in decolonization of patients with Candida auris: Learnings from a county health care system

BACKGROUND

Candida auris (CA) is an organism that has spread globally over the last decade. We conducted a quality improvement project with the aim of decreasing or eliminating skin colonization of patients with CA through a modified bathing protocol.

METHODS

An isotonic hypochlorite solution was added to routine bathing protocols for hospitalized patients colonized with CA. Weekly skin swabs from axillary and inguinal areas were tested for the presence of CA using polymerase chain reaction and culture. Multidisciplinary efforts, such as environmental terminal cleaning, dedicated equipment, education, and signage were reinforced among staff to improve patient outcomes.

RESULTS

A total of 24 patients were included. After 4 weeks of a modified bathing protocol, 81.2% of the patients remained colonized with CA. Three patients were discharged safely to their homes and 3 were transferred to long-term care acute hospitals. Nine patients remained hospitalized after 60 days. Localized rash was reported in 3 patients, which resolved after discontinuation of the product.

CONCLUSIONS

Modification of our bathing protocols by including an isotonic hypochlorite solution did not lead to skin decolonization of CA. Further studies are needed to identify effective measures to eradicate, eliminate or reduce colonization.

Cellular apoptosis and cell cycle arrest as potential therapeutic targets for eugenol derivatives in Candida auris

Candida auris, the youngest Candida species, is known to cause candidiasis and candidemia in humans and has been related to several hospital outbreaks. Moreover, Candida auris infections are largely resistant to the antifungal drugs currently in clinical use, necessitating the development of novel medications and approaches to treat such infections. Following up on our previous studies that demonstrated eugenol tosylate congeners (ETCs) to have antifungal activity, several ETCs (C1-C6) were synthesized to find a lead molecule with the requisite antifungal activity against C. auris. Preliminary tests, including broth microdilution and the MUSE cell viability assay, identified C5 as the most active derivative, with a MIC value of 0.98 g/mL against all strains tested. Cell count and viability assays further validated the fungicidal activity of C5. Apoptotic indicators, such as phosphatidylserine externalization, DNA fragmentation, mitochondrial depolarization, decreased cytochrome c and oxidase activity and cell death confirmed that C5 caused apoptosis in C. auris isolates. The low cytotoxicity of C5 further confirmed the safety of using this derivative in future studies. To support the conclusions drawn in this investigation, additional in vivo experiments demonstrating the antifungal activity of this lead compound in animal models will be needed.

Improving the production of the micafungin precursor FR901379 in an industrial production strain

BACKGROUND

Micafungin is an echinocandin-type antifungal agent used for the clinical treatment of invasive fungal infections. It is semisynthesized from the sulfonated lipohexapeptide FR901379, a nonribosomal peptide produced by the filamentous fungus Coleophoma empetri. However, the low fermentation efficiency of FR901379 increases the cost of micafungin production and hinders its widespread clinical application.

RESULTS

Here, a highly efficient FR901379-producing strain was constructed via systems metabolic engineering in C. empetri MEFC09. First, the biosynthesis pathway of FR901379 was optimized by overexpressing the rate-limiting enzymes cytochrome P450 McfF and McfH, which successfully eliminated the accumulation of unwanted byproducts and increased the production of FR901379. Then, the functions of putative self-resistance genes encoding β-1,3-glucan synthase were evaluated in vivo. The deletion of CEfks1 affected growth and resulted in more spherical cells. Additionally, the transcriptional activator McfJ for the regulation of FR901379 biosynthesis was identified and applied in metabolic engineering. Overexpressing mcfJ markedly increased the production of FR901379 from 0.3 g/L to 1.3 g/L. Finally, the engineered strain coexpressing mcfJ, mcfF, and mcfH was constructed for additive effects, and the FR901379 titer reached 4.0 g/L under fed-batch conditions in a 5 L bioreactor.

CONCLUSIONS

This study represents a significant improvement for the production of FR901379 and provides guidance for the establishment of efficient fungal cell factories for other echinocandins.

Emergence of Candida auris in intensive care units in Algeria

Background

Currently, Candida auris is among the most serious emerging pathogens that can be associated with nosocomial infections and outbreaks in intensive care units. Clinicians must be able to identify and manage it quickly.

Objective

Here, we report for the first time in Algeria seven cases of C. auris infection or colonisation.

Methods and Results

The strains were isolated from clinical sites including bronchial aspirates (n = 4), wound swabs (n = 1), urine sample (n = 1) and peritoneal fluid (n = 1), in patients admitted to the intensive care unit. Candida auris was identified both by MALDI‐TOF and by sequencing the ITS region and the D1/D2 domain. Antifungal susceptibility testing was performed using the E‐test method. Non‐wildtype susceptibility was observed for five strains against fluconazole, itraconazole, voriconazole and caspofungin. Genotyping showed the presence of four clades (I–IV) in one hospital.

Conclusions

Appropriate antifungal treatments with rapid and accurate microbial identification are the cornerstone for the management and control of C. auris infections.

Echinocandins - structure, mechanism of action and use in antifungal therapy

With increasing number of immunocompromised patients as well as drug resistance in fungi, the risk of fatal fungal infections in humans increases as well. The action of echinocandins is based on the inhibition of β-(1,3)-d-glucan synthesis that builds the fungal cell wall. Caspofungin, micafungin, anidulafungin and rezafungin are semi-synthetic cyclic lipopeptides. Their specific chemical structure possess a potential to obtain novel derivatives with better pharmacological properties resulting in more effective treatment, especially in infections caused by Candida and Aspergillus species. In this review we summarise information about echinocandins with closer look on their chemical structure, mechanism of action, drug resistance and usage in clinical practice. We also introduce actual trends in modification of this antifungals as well as new methods of their administration, and additional use in viral and bacterial infections.

Candida auris: A Quick Review on Identification, Current Treatments, and Challenges

Candida auris is a novel and major fungal pathogen that has triggered several outbreaks in the last decade. The few drugs available to treat fungal diseases, the fact that this yeast has a high rate of multidrug resistance and the occurrence of misleading identifications, and the ability of forming biofilms (naturally more resistant to drugs) has made treatments of C. auris infections highly difficult. This review intends to quickly illustrate the main issues in C. auris identification, available treatments and the associated mechanisms of resistance, and the novel and alternative treatment and drugs (natural and synthetic) that have been recently reported.